Cat boxes formed of a cover and a bottom are commonly used to collect cat feces and urine. For reducing bacteria or odor buildup, various liners have been provided for covering a bottom of the cat box. U.S. Pat. No. 5,850,798, issued to the present inventor and describing one such liner for a cat box bottom, achieves reduction in bacteria or odor buildup. However, even further improvements in reducing bacteria or odor buildup would be desirable.